kernel/arch/powerpc/platforms/powernv/idle.c

   1 /*
   2  * PowerNV cpuidle code
   3  *
   4  * Copyright 2015 IBM Corp.
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/mm.h>
  14 #include <linux/slab.h>
  15 #include <linux/of.h>
  16 #include <linux/device.h>
  17 #include <linux/cpu.h>
  18
  19 #include <asm/firmware.h>
  20 #include <asm/machdep.h>
  21 #include <asm/opal.h>
  22 #include <asm/cputhreads.h>
  23 #include <asm/cpuidle.h>
  24 #include <asm/code-patching.h>
  25 #include <asm/smp.h>
  26
  27 #include "powernv.h"
  28 #include "subcore.h"
  29
  30 static u32 supported_cpuidle_states;
  31
  32 int pnv_save_sprs_for_winkle(void)
  33 {
  34         int cpu;
  35         int rc;
  36
  37         /*
  38          * hid0, hid1, hid4, hid5, hmeer and lpcr values are symmetric accross
  39          * all cpus at boot. Get these reg values of current cpu and use the
  40          * same accross all cpus.
  41          */
  42         uint64_t lpcr_val = mfspr(SPRN_LPCR) & ~(u64)LPCR_PECE1;
  43         uint64_t hid0_val = mfspr(SPRN_HID0);
  44         uint64_t hid1_val = mfspr(SPRN_HID1);
  45         uint64_t hid4_val = mfspr(SPRN_HID4);
  46         uint64_t hid5_val = mfspr(SPRN_HID5);
  47         uint64_t hmeer_val = mfspr(SPRN_HMEER);
  48
  49         for_each_possible_cpu(cpu) {
  50                 uint64_t pir = get_hard_smp_processor_id(cpu);
  51                 uint64_t hsprg0_val = (uint64_t)&paca[cpu];
  52
  53                 /*
  54                  * HSPRG0 is used to store the cpu's pointer to paca. Hence last
  55                  * 3 bits are guaranteed to be 0. Program slw to restore HSPRG0
  56                  * with 63rd bit set, so that when a thread wakes up at 0x100 we
  57                  * can use this bit to distinguish between fastsleep and
  58                  * deep winkle.
  59                  */
  60                 hsprg0_val |= 1;
  61
  62                 rc = opal_slw_set_reg(pir, SPRN_HSPRG0, hsprg0_val);
  63                 if (rc != 0)
  64                         return rc;
  65
  66                 rc = opal_slw_set_reg(pir, SPRN_LPCR, lpcr_val);
  67                 if (rc != 0)
  68                         return rc;
  69
  70                 /* HIDs are per core registers */
  71                 if (cpu_thread_in_core(cpu) == 0) {
  72
  73                         rc = opal_slw_set_reg(pir, SPRN_HMEER, hmeer_val);
  74                         if (rc != 0)
  75                                 return rc;
  76
  77                         rc = opal_slw_set_reg(pir, SPRN_HID0, hid0_val);
  78                         if (rc != 0)
  79                                 return rc;
  80
  81                         rc = opal_slw_set_reg(pir, SPRN_HID1, hid1_val);
  82                         if (rc != 0)
  83                                 return rc;
  84
  85                         rc = opal_slw_set_reg(pir, SPRN_HID4, hid4_val);
  86                         if (rc != 0)
  87                                 return rc;
  88
  89                         rc = opal_slw_set_reg(pir, SPRN_HID5, hid5_val);
  90                         if (rc != 0)
  91                                 return rc;
  92                 }
  93         }
  94
  95         return 0;
  96 }
  97
  98 static void pnv_alloc_idle_core_states(void)
  99 {
 100         int i, j;
 101         int nr_cores = cpu_nr_cores();
 102         u32 *core_idle_state;
 103
 104         /*
 105          * core_idle_state - First 8 bits track the idle state of each thread
 106          * of the core. The 8th bit is the lock bit. Initially all thread bits
 107          * are set. They are cleared when the thread enters deep idle state
 108          * like sleep and winkle. Initially the lock bit is cleared.
 109          * The lock bit has 2 purposes
 110          * a. While the first thread is restoring core state, it prevents
 111          * other threads in the core from switching to process context.
 112          * b. While the last thread in the core is saving the core state, it
 113          * prevents a different thread from waking up.
 114          */
 115         for (i = 0; i < nr_cores; i++) {
 116                 int first_cpu = i * threads_per_core;
 117                 int node = cpu_to_node(first_cpu);
 118
 119                 core_idle_state = kmalloc_node(sizeof(u32), GFP_KERNEL, node);
 120                 *core_idle_state = PNV_CORE_IDLE_THREAD_BITS;
 121
 122                 for (j = 0; j < threads_per_core; j++) {
 123                         int cpu = first_cpu + j;
 124
 125                         paca[cpu].core_idle_state_ptr = core_idle_state;
 126                         paca[cpu].thread_idle_state = PNV_THREAD_RUNNING;
 127                         paca[cpu].thread_mask = 1 << j;
 128                 }
 129         }
 130
 131         update_subcore_sibling_mask();
 132
 133         if (supported_cpuidle_states & OPAL_PM_WINKLE_ENABLED)
 134                 pnv_save_sprs_for_winkle();
 135 }
 136
 137 u32 pnv_get_supported_cpuidle_states(void)
 138 {
 139         return supported_cpuidle_states;
 140 }
 141 EXPORT_SYMBOL_GPL(pnv_get_supported_cpuidle_states);
 142
 143
 144 static void pnv_fastsleep_workaround_apply(void *info)
 145
 146 {
 147         int rc;
 148         int *err = info;
 149
 150         rc = opal_config_cpu_idle_state(OPAL_CONFIG_IDLE_FASTSLEEP,
 151                                         OPAL_CONFIG_IDLE_APPLY);
 152         if (rc)
 153                 *err = 1;
 154 }
 155
 156 /*
 157  * Used to store fastsleep workaround state
 158  * 0 - Workaround applied/undone at fastsleep entry/exit path (Default)
 159  * 1 - Workaround applied once, never undone.
 160  */
 161 static u8 fastsleep_workaround_applyonce;
 162
 163 static ssize_t show_fastsleep_workaround_applyonce(struct device *dev,
 164                 struct device_attribute *attr, char *buf)
 165 {
 166         return sprintf(buf, "%u\n", fastsleep_workaround_applyonce);
 167 }
 168
 169 static ssize_t store_fastsleep_workaround_applyonce(struct device *dev,
 170                 struct device_attribute *attr, const char *buf,
 171                 size_t count)
 172 {
 173         cpumask_t primary_thread_mask;
 174         int err;
 175         u8 val;
 176
 177         if (kstrtou8(buf, 0, &val) || val != 1)
 178                 return -EINVAL;
 179
 180         if (fastsleep_workaround_applyonce == 1)
 181                 return count;
 182
 183         /*
 184          * fastsleep_workaround_applyonce = 1 implies
 185          * fastsleep workaround needs to be left in 'applied' state on all
 186          * the cores. Do this by-
 187          * 1. Patching out the call to 'undo' workaround in fastsleep exit path
 188          * 2. Sending ipi to all the cores which have atleast one online thread
 189          * 3. Patching out the call to 'apply' workaround in fastsleep entry
 190          * path
 191          * There is no need to send ipi to cores which have all threads
 192          * offlined, as last thread of the core entering fastsleep or deeper
 193          * state would have applied workaround.
 194          */
 195         err = patch_instruction(
 196                 (unsigned int *)pnv_fastsleep_workaround_at_exit,
 197                 PPC_INST_NOP);
 198         if (err) {
 199                 pr_err("fastsleep_workaround_applyonce change failed while patching pnv_fastsleep_workaround_at_exit");
 200                 goto fail;
 201         }
 202
 203         get_online_cpus();
 204         primary_thread_mask = cpu_online_cores_map();
 205         on_each_cpu_mask(&primary_thread_mask,
 206                                 pnv_fastsleep_workaround_apply,
 207                                 &err, 1);
 208         put_online_cpus();
 209         if (err) {
 210                 pr_err("fastsleep_workaround_applyonce change failed while running pnv_fastsleep_workaround_apply");
 211                 goto fail;
 212         }
 213
 214         err = patch_instruction(
 215                 (unsigned int *)pnv_fastsleep_workaround_at_entry,
 216                 PPC_INST_NOP);
 217         if (err) {
 218                 pr_err("fastsleep_workaround_applyonce change failed while patching pnv_fastsleep_workaround_at_entry");
 219                 goto fail;
 220         }
 221
 222         fastsleep_workaround_applyonce = 1;
 223
 224         return count;
 225 fail:
 226         return -EIO;
 227 }
 228
 229 static DEVICE_ATTR(fastsleep_workaround_applyonce, 0600,
 230                         show_fastsleep_workaround_applyonce,
 231                         store_fastsleep_workaround_applyonce);
 232
 233 static int __init pnv_init_idle_states(void)
 234 {
 235         struct device_node *power_mgt;
 236         int dt_idle_states;
 237         u32 *flags;
 238         int i;
 239
 240         supported_cpuidle_states = 0;
 241
 242         if (cpuidle_disable != IDLE_NO_OVERRIDE)
 243                 goto out;
 244
 245         if (!firmware_has_feature(FW_FEATURE_OPALv3))
 246                 goto out;
 247
 248         power_mgt = of_find_node_by_path("/ibm,opal/power-mgt");
 249         if (!power_mgt) {
 250                 pr_warn("opal: PowerMgmt Node not found\n");
 251                 goto out;
 252         }
 253         dt_idle_states = of_property_count_u32_elems(power_mgt,
 254                         "ibm,cpu-idle-state-flags");
 255         if (dt_idle_states < 0) {
 256                 pr_warn("cpuidle-powernv: no idle states found in the DT\n");
 257                 goto out;
 258         }
 259
 260         flags = kzalloc(sizeof(*flags) * dt_idle_states, GFP_KERNEL);
 261         if (of_property_read_u32_array(power_mgt,
 262                         "ibm,cpu-idle-state-flags", flags, dt_idle_states)) {
 263                 pr_warn("cpuidle-powernv: missing ibm,cpu-idle-state-flags in DT\n");
 264                 goto out_free;
 265         }
 266
 267         for (i = 0; i < dt_idle_states; i++)
 268                 supported_cpuidle_states |= flags[i];
 269
 270         if (!(supported_cpuidle_states & OPAL_PM_SLEEP_ENABLED_ER1)) {
 271                 patch_instruction(
 272                         (unsigned int *)pnv_fastsleep_workaround_at_entry,
 273                         PPC_INST_NOP);
 274                 patch_instruction(
 275                         (unsigned int *)pnv_fastsleep_workaround_at_exit,
 276                         PPC_INST_NOP);
 277         } else {
 278                 /*
 279                  * OPAL_PM_SLEEP_ENABLED_ER1 is set. It indicates that
 280                  * workaround is needed to use fastsleep. Provide sysfs
 281                  * control to choose how this workaround has to be applied.
 282                  */
 283                 device_create_file(cpu_subsys.dev_root,
 284                                 &dev_attr_fastsleep_workaround_applyonce);
 285         }
 286
 287         pnv_alloc_idle_core_states();
 288 out_free:
 289         kfree(flags);
 290 out:
 291         return 0;
 292 }
 293 machine_subsys_initcall(powernv, pnv_init_idle_states);